短叶片长度对固液离心泵内流场影响的模拟研究

为了研究短叶片长度对长短叶片离心泵叶轮内固液两相流场的影响,应用CFD软件对5种不同短叶片长度的离心泵中的固液两相流场进行数值模拟,分析并对比5种离心泵中压力及固相体积浓度变化规律.结果显示:5种离心泵中的压力沿着半径增大方向呈增大趋势;且相同半径处,工作面压力总是大于吸力面;在一定程度上减小短叶片长度,压力分布更均匀,颗粒浓度的变化曲线更平缓,同时叶轮中固相颗粒的高浓度区域大大减小,从而能够减弱各种不稳定因素的影响,保持良好的流动状态,提高离心泵的水力性能和抗磨损性能.所得结论为离心泵的改良和设计提供非常有价值的理论基础.     

基于PLC的固液两相流泵控制系统的设计

针对固液两相流泵运行时由于料浆过多或过少引起输送系统无法正常工作的问题,文章介绍了一种基于PLC的固液两相流泵控制系统的设计,详细介绍了系统软、硬件设计。该系统利用液位传感器检测原料槽和储料槽的液位信息,PLC根据该信息控制固液两相流泵的启停,并可进行光电报警。仿真结果表明了该控制系统的正确性和有效性。现场实际应用也验证了其稳定性和可靠性。     

高速燃油离心泵内流场分析和气蚀过程仿真

采用混合两相流模型和气蚀模型,采用两种网格技术多参考系模型和滑移网格模型对某型航空发动机高速燃油加力离心泵内流场和气蚀过程进行了二维数值仿真.首先使用多参考系模型得到稳态非气蚀流场,然后作为初始条件引入滑移网格技术同时加人气蚀模型对气蚀全过程进行了瞬态仿真.不仅良好地模拟出泵腔内空泡初生、发展、消失的瞬态全过程,同时发现了稳定的瞬态压力场和气泡体积分数场的周期性发展规律,并揭示这一规律由排出管引起.详细分析了气蚀易发生位置的空间分布,排出管对气蚀发生的影响,高度空化流中蜗室出口壁面处气蚀破坏及其成因.仿真结果与实物气蚀破坏情况符合良好,对认识高速离心泵内燃油流动,预测并克服气蚀发生有指导意义.     

气液两相流空隙率测量方法微重力环境应用研究

微重力环境下气液两相流空隙率测量是载人航天器需解决的关键技术之一。通过对当前常重力环境下气液两相流空隙率测量方法的特点和微重力环境对气液两相流空隙率测量的影响分析,提出了满足微重力环境气液两相流空隙率测量方法的基本要求,对当前空隙率测量方法在微重力环境应用的可行性进行了分析,并给出了相应建议。     

槽式孔板的气液两相流测量特性

为了准确计量气液两相流量,选用槽式孔板作为一次传感元件、以空气/水为测量介质,进行了一系列的实验.介于两相流动的随机波动特征,对气液两相流流过槽式孔板时产生的差压信号进行了处理,提取出能够反映气液流量变化的几个统计特征量,总结了差压信号的平均值、标准差、自相关最大值和(0,4)Hz频段功率随气液流量变化而变化的规律,为两相流流量计的开发奠定了基础.     

一种气液两相流气相参数图像检测方法

介绍了一种运用图像处理技术检测气液两相流参数的新方法,针对气液两相中气泡目标对比度低的特点,提出先对待处理图像进行分形增强,运用改进的Canny算子检测出气泡目标边缘,在经过填充和标记后检测出两相流图像面积、圆形度、截面含气率等参数,为气液传质效率建模提供了基础;实践证明该方法抗干扰能力强,是一种实用可行的参数检测方法.     

弹状流工况下的气液两相流双参数测量

由于两相流动的复杂性,利用实验测量手段实现两相流的准确测量成为目前研究的热点.在弹状流流型的工况条件下选取了30个实验点,利用新型气液两相流检测装置进行测量实验,结果表明:液相含率测量相对误差在4.3％以内,总流量测量相对误差在1.6％以内,为气液两相流双参数测量研究提供了一种新的思路.     

气液两相流红外检测技术研究

气液两相流检测是目前载人航天电解制氧装置急需解决的关键技术之一。设计一种基于红外检测的传感器实现对低浓度液/气含量的测量,通过对脉宽调制(PWM)驱动红外发射、TEC恒温控制、抗干扰等技术研究,成功制得气液两相流传感器。实验表明,该传感器可测量液态水含量0～30%的气液两相流,系统误差优于10%,能够满足电解制氧装置两相流检测的需要。     

气/液两相泡状流相关流速测量系统的研究

气/液两相流是自然界和工业过程中一种非常典型、复杂的多相流形态,其中,离散相如气泡的运动速度、尺寸、位置以及两相流流型等参数的监测是一个很重要的研究课题.本文介绍了利用电容层析成像技术和相关流速测量技术对气/液两相泡状流的离散相速度及其分布测量的研究.     

一种两相流浓度测量传感器的仿真研究

在石油,化工等诸多生产领域的生产过程中,两相流各种参数的在线实时测量与控制是生产稳定可靠运行的重要保证,其中相浓度就是一项十分重要的参数;为了避免电容传感器结构对相浓度的影响,设计了一种同轴电容传感器,利用有限元分析软件ANSYS 对其进行了分析,在不同浓度相同流型及相同浓度不同流型两种实验方案下进行了大量实验;结果表明,该结构传感器具有均匀的敏感场分布和较高的灵敏度,而且该结构传感器电容值与流型无关,只与浓度变化有关;因此该结构传感器可应用于气/液、液/液两相流浓度参数检测,具有广阔的应用前景.     

Investigation of an efficient shape optimization procedure for centrifugal pump impeller using eagle strategy algorithm and ANN (case study: slurry flow)

Investigation an efficient shape optimization method for centrifugal pump and other turbo-machine is significant to reduce time consumption of process and increase accuracy and modification. For analysis an efficient shape optimization procedure, slurry flow in centrifugal pump is investigated. Since a centrifugal water pump has been not designed to carry out slurry flows, its performance decreases and energy consumption of this kind of pump increases. Therefore, improvement of performance and reduction of energy consumed for these pumps are the major issues. Since the performance of a centrifugal pump strictly depends on its impeller shape, in this study, the shape of impeller was optimized in order to achieve a higher efficiency for slurry flow. To optimize the impeller geometry and to improve the performance of Berkeh 32–160 pump as for the case study, Artificial Neural Networks (ANN) and Eagle Strategy (ES) algorithms have been coupled with a validated 3D Navier–Stokes equations for two phase flow based on Eulerian-Eulerian model. In the next step, the pump experimentally tested in an established slurry flow test rig in laboratory. Measured data were used to verify the numerical results of initial pump with slurry flow. Finally, the complete numerical characteristic curves of the pump with the optimized impeller were compared to the validated numerical characteristic curves of that with the initial impeller to verify optimization. An efficiency improvement of 3.33% at only 9.9% increasing of head has been obtained for optimized geometry. The results indicated a reasonable improvement in the optimal design of pump impeller and a higher performance using the ES algorithm. Furthermore the ES and PSO algorithm was compared and results shows that ES is efficient than PSO algorithm in this application and this methodology is more efficient than other surrogate methods.     

基于模型的离心泵故障诊断设计

针对离心泵这一工业技术过程中的基本设备,开展基于解析模型的故障诊断方法设计研究。首先在对离心泵工作机理进行详细分析的基础上,建立离心泵管道系统的传递函数模型,然后考虑电动机定子绕组发生匝间短路,建立其在故障情况下的模型。接着,基于所构建的模型,采用因式分解方法设计残差产生器以实时检测匝间短路故障。最后,通过Matlab/Simulink仿真验证了所提方法的有效性和优越性。     

Microfabricated centrifugal pump driven by an integrated synchronous micromotor

This paper presents the development of a new design of the microfabricated centrifugal force pump. The pumping concept is based on running an impeller (a rotor including permanent magnets carrying straight and backward blades) within an integrated synchronous motor, which can be operated at different rotational speeds to pump water. The impeller is 5.5 mm in diameter, and is 1.5 mm in height. This micropump with 7-straight-blade impeller can operate smoothly up to a rotational speed of 9000 rpm. It can deliver a non-pulsating maximum flow rate of up to 12 ml/min and allows water to be pumped up to a 24 cm water head. Additionally, the micropump with the backward-blade-impeller pump delivered a flow rate of up to 14.3 ml/min. at a rotational speed of 11,400 rpm with no back pressure. The micropump was patterned using a series of microfabrication processes including sputtering, photolithography and electroplating within a clean room. Such a pump can be integrated into a system of a compact size and can provide a wide range of flow rates. It could also be a promising device for use within biological and micro biomedical fields. To our knowledge, this is the smallest centrifugal pump in the world with an integrated electromagnetic synchronous motor that offers such high flow rates.

     

离心泵变频调速与节流分程协调节能控制

离心泵的变频调速是目前广泛采用的流量调节方法,高效节能是其最大优点,但是当流量降低时,可能造成压头过低而影响后续流程.对此,提出离心泵的变频调速与节流分程协调节能控制方法,当阀后压力大于一定值时,由流量控制器调节离心泵转速以改变泵的出口流量,当阀后压力小于一定值时,由流量控制器调节阀门开度以保持控制点需要的实际压头基本恒定,而中间段由转速和阀门开度协调控制,从而能够同时满足管路控制点所需的压力及流量.实验模拟效果证明了控制方案的可行性,并且流量与压力二者分程协调控制的节能效果显著.     

叶顶间隙对离心泵性能影响的数值模拟研究

离心泵的几何结构复杂,所以其内部流场也极其复杂并呈强烈的三维紊流特性,由于目前的理论水甲和实验手段的限制,只能依靠精确的计算机仿真,才能获得其内部流场的详细情况,以便进行设计和优化.为了研究叶顶间隙对叶轮内部流场及性能的影响,对闭式离心泵叶轮和有间隙的半开式离心泵叶轮共同进行了计算机仿真.在所得计算结果基础上详细对比分析了离心泵内部流场的特性,捕捉到了叶轮通道内部的二次流现象.结果表明:随着叶顶间隙增大,叶顶问隙泄漏流动会使叶轮性能下降,二次流强度增加.从而说明计算机数值模拟方法,可以弥补实验方法的不足,用来研究叶顶间隙流动的影响,为离心泵的水力设计和优化提供依据.     

某型涡扇发动机进口空气流量及附面层的测量与计算

航空发动机的空气流量是发动机的重要性能参数,其测量的准确性对航空发动机的设计具有重要的意义。根据以往的发动机进口空气流量的测量和计算经验,采用新型附面层压力组合耙测量发动机进口流场信息,建立了发动机空气流量计算模型,并使用面积分块和附面层修正的方法得到发动机空气流量。试验结果表明发动机中间状态空气流量测量值与设计值基本一致,附面层对空气流量的影响大约为2%～3%,新型的附面层压力组合耙能够丰富且准确地获得发动机进口流场及其附面层的信息。     

Numerical flow-field analysis and design optimization of a high-energy first-stage centrifugal pump impeller

Described is the numerical flow-field analysis and design optimization of the first-stage impellers of a so-called high-energy centrifugal pump having two single-suction first-stage impellers and one double-suction second stage impeller. This study has been carried out with the aid of three-dimensional computational-fluid-dynamics calculations, employing the potential-flow approximation of the governing equations. The study was conducted because the first-stage impellers of the pump considered appeared to suffer from severe premature wear due to cavitation attack on the vane leading edges, which situation had to be improved. The analysis carried out for the existing design produced suggestions for improvement, and based on these suggestions a new first-stage impeller design was developed. Subsequently, this new design was numerically analyzed to substantiate its potentially better (cavitation) performance. It appeared that the blade inlet angle of the original impeller design was too excessive at mid span, causing best cavitation performance to occur at 160 percent of the rated flow. The new design has its best cavitation point at the rated flow, and will not suffer from premature wear due to cavitation attack like the existing design. Received: 1 March 1999 / Accepted: 21 September 1999     

Gap Flow Simulation Methods in High Pressure Variable Displacement Axial Piston Pumps

High pressure variable displacement axial piston pumps are subject to complex dynamic phenomena. Their analysis is difficult, additionally complicated by leakage of the working fluid. Analytically gap flow is calculated with the Reynolds equation which describes the pressure distribution in a thin lubricating layer. The paper presents various approaches to analyze gap flow both in traditional axial piston pump and novel type of hydraulic pump, designed at the Polish Gdansk Institute of Technology. Because of large aspect ratio between the height of the gap and the size of pump elements, the authors present the numerical simulation approach using a local model to define a lubrication gap, linked to a global model of a pump from which boundary conditions were imported. User defined functions implemented in Fluent and Excel were used to calculate the pressure and velocity fields and assess the fluid flow rate.     

PIV measurement on internal instantaneous flows of a centrifugal pump

In this paper,the internal flow field in a centrifugal pump working at the design flow rate operating condition has been measured using the particle image velocimetry(PIV)technique with the fluorescent particles and the index-matched fluid technology.The index-marching fluid with the same refractive index as the transparent material has been prepared and applied in the present test of pump with geometrical complex walls.The comparison between velocity distributions of PIV results both with and without fluor...